Methods for perforating an earth formation

ABSTRACT

As a preferred mode for practicing the invention disclosed herein, one or more sets of selectively-fired perforating devices are positioned in a well bore and the first of two adjacent devices is actuated for producing a first perforation extending along a selected perforating axis into an adjacent earth formation. The second perforating device is then positioned immediately adjacent to the previous position of the first perforating device and directed along a second perforating axis closely paralleling that of the first perforation. Upon actuation of the second device, a second perforation is produced which is contiguous with the first perforation and effective for displacing compacted, crushed formation materials from around at least a portion of the second perforation to improve the productivity of at least this second perforation.

United States Patent 1151 3,706,340 Schuster Dec; 19, 1972 1541 METHODS FOR PERFORATING AN 3,430,711 3/1969 Taggart ..175/452 1 EARTH FORMATION 3,542,141 11/1970 Voetter ..175/452 [72] Inventor. Nick A. Schuster, Dar1en,Conn. Primary Examiner David H. Brown [73] Assignee: Schlumberger Technology Corpora- Attorney-Emest R. Archambeau, Jr., Stewart F. tion, New York, NY. Moore, David L. Moseley, Edward M. Roney, William R. Sherman, Jerry M. Presson, Michael J. Ber er and 22 Filed: April 7,1971 James C. Kesterson g [21] Appl. No.: 132,014

[57] ABSTRACT 52 us. c1 ..166/297, l75/4.6 As a preferred mode for practicing the invention 511 1111.01. ..E21b43/117 closed herein, one or more Sets of Selectively-fired [58] Field of Search ..175/4.5, 4.51, 4.52, 4.53, perforating devices are Positioned in a well bore and 175 455 45 4 1 /297 55 55 1 100 the first of two adjacent devices is actuated for 3 producing a first perforation extending along a selected perforating axis into an adjacent earth forma- [56] References Cited tion. The second perforating device is then positioned immediately adjacent to the previous position of the UNITED STATES PATENTS first perforating device and directed along a second erforatin axis closel arallelin that of the first er- 3,347,315 lO/l967 Lanmon "175/452 i a g g of second device: a i second perforation is produced which is contiguous with the first perforation and effective for displacing Church compacted, crushed formation materials from around 3,043,379 7/1962 Porter ..175/4.6 X at least a portion of the Second perforation to improve g ti 1 the productivity of at least this second perforation. 1 e 3,347,164 V 10/1967 Baks et al. ..175/4.6 X 11 Claims, 6 Drawing Figures PMENIEB DEC 1- 9 I972 33; 7 05; 340

48 NIIC g'cuurTeL F l G. 5 INVENTOR ATTORNEY METHODS FOR PERFORATING AN EARTH FORMATION Heretofore, substantial efforts have been directed toward devising completion apparatus and techniques for perforating a well bore and then injecting formation-consolidating agents in those situations where the perforated formation is substantially composed of loose or incompetent formation materials which must be chemically bonded to limit the subsequent production of these loose materials. For example, in U.S. Pat. No. 3,153,449, unique methods and apparatus are disclosed for producing a single perforation that is first flushed of loose formation materials and then injected with a suitable treating agent for consolidating the immediately-surrounding portions of the formation. Similarly, U.S. Pat. No. 3,329,204, U.S. Pat. No. 3,347,314 and U.S. Pat. No. 3,347,315 respectively disclose new and improved completion techniques and tools for perforating a well casing at two closely-spaced points and, after clearing the perforations of loose formation materials, injecting suitable consolidating agents.

It will be appreciated, however, that none of these completion techniques or injection tools are particularly suited for perforating relatively-competent formations which do not require the injection of a consolidating agent. Even if such techniques or tools were em ployed in such situations, only one or, at best, two usable perforations would be produced for each operation. Thus, if a formation interval of substantial length required perforation at several points, the aforementioned tools would have to be repetitively employed before the entire interval could be adequately perforated.

Of far more significance, however, it has been found that a perforation in a well-consolidated formation will often be incapable of efficient production even after the perforation has been substantially cleaned of the usual shaped charge debris which typically lines the walls of the perforation. Experiments have shown that, in many instances, such low rates of productivity can be significantly attributed to the presence of a relativelyimpervious envelope of tightly-compacted, crushed formation materials surrounding at least a major portion of the perforation. As a result, even though shaped charge debris and loose materials are cleared from the perforation, these experiments have shown that the full production capability of the perforation cannot be realized unless at least a portion of this tightly-compacted envelope is removed or broken down.

Accordingly, it is an object of the present invention to provide new and improved methods for producing perforations at one or more locations along a well bore interval traversing competent earth formations in such a manner that at least a portion of the envelope of crushed, compacted formation materials surrounding such perforations is removed.

This and other objects of the present invention are attained by actuating a first perforating device for producing a first perforation which is directed along a selected perforating axis and extends into an earth formation ahead of the perforating device. Thereafter, a second perforating device is positioned so that its perforating axis is either closely parallel to the first axis or is very slightly converged toward an intersection with the axis of the first perforation. In this manner, upon actuation of the second perforating device, a second perforation is produced which closely parallels and is substantially contiguous with the first perforation so that crushed formation materials in and around the walls of the second perforation will be displaced into the first perforation by the force of the second perforating jet to clear the walls of at least part of the second perforation of such compacted materials.

The novel features of the present invention are set forth with particularity in the appended claims. The invention, together with further objects and advantages thereof, may be best understood by way of the following description of exemplary methods employing the principles of the invention as illustrated in the accompanying drawings, in which:

FIGS. 1 and 2 schematically depict one embodiment of perforating apparatus as it will successively appear while positioned in a well bore for conducting a perforating operation in accordance with the principles of the present invention;

FIGS. 3 and 4 are enlarged cross-sectional views of typical perforations which have been produced in accordance with the methods of the present invention by the sequential operation of the apparatus depicted in FIGS. 1 and 2; and

FIGS. 5 and 6 are cross-sectional views respectively taken along the lines 5-5 and 66 of FIG. 4.

Turning now to FIG. 1, a somewhat-schematic representation is shown of perforating apparatus 10 which may be employed for practicing the methods of the present invention. As illustrated, the perforating apparatus 10 is depicted as it will appear while suspended in the usual manner from a typical electrical cable 11 within a well casing 12 secured in a borehole 13 by an annular column of cement 14. The suspension cable 11 is spooled from a powered winch (not shown) located at the earthssurface and adapted for selectively moving the perforating apparatus 10 through the casing 1 1 and into position adjacent to an earth formation 15 which is to be perforated. A suitable power supply (not shown) is provided at the surface for selectively supplying electrical current to the suspension cable 11. As is typical, the perforating apparatus 10 further includes suitable depth-indicating means such as a casing-collar locator 16 arranged on or near the upper end of the tool. For reasons that will subsequently be explained in greater detail, electrical control means 17 are cooperatively arranged on the lower portion of the perforating apparatus 10.

The perforating apparatus 10 further includes an elongated body or carrier 18 having two or more separated fluid-tight compartments, as at 19 and 20, arranged therein at longitudinally-spaced intervals. The perforating apparatus 10 is further provided with a plurality of shaped charges, as at 21 and 22, respectively mounted in each of the compartments l9 and 20 with their forward ends facing lateral ports in the forward wall of the carrier 18 that are each sealingly closed by an expendible port-closure member as at 23. It will,

. however, be appreciated that whenever one of the dinally-spaced compartments, as at 19 and 20, so that a corresponding number of shaped charges, as at 21 and 22, can be arranged therein. However, only the one set of the shaped charges 21 and 22 is illustrated for simplifying the drawings and facilitating the explanation of the methods of the present invention. Although the shaped charges 21 and 22 may, of course, be of any suitable design, the charges may be similar or identical to those shown in Pat. No. 3,329,218.

As illustrated in FIG. 1, the perforating apparatus 10 includes a wall-anchoring assembly 24 which is cooperatively mounted on the lower end of the carrier 18. The anchoring assembly 24 includes a tubular housing 25 which is coaxially mounted and co-rotatively secured, as by a spline and groove arrangement 26, on a depending extension member 27 of the carrier 18 for limited longitudinal travel along the extension. Two or more pairs of outwardly-bowed springs, as at 28, are mounted in an upright position at circumferentiallyspacedv intervals around the tubular housing 25 and biased outwardly for maintaining sliding frictional engagement with the well casing 12. As is typical, the wall-anchoring springs 28 are cooperatively arranged to provide a sufficient anchoring force for temporarily securing the tubular housing 25 in relation to the casing 12 when the carrier 18 is to be shifted relative thereto. This anchoring force is, of course, insufficient to unduly hinder the passage of the perforating apparatus 10 through the casing 12. To limit the extent of relative longitudinal movement between the carrier 18 and the anchoring assembly 24, oppositely-facing shoulders 29 and 30 are respectively arranged on the carrier and the lowerend of the depending member 27 for engagement with shoulders 31 and 32 defined by the upper and lower ends of the housing 25 so that the maximum span of longitudinal travel of the carrier in relation to the anchoring assembly will be slightly less than the longitudinal spacing between the perforating axes 33 and 34 of each set of the shaped charges, as at 21 and 22. The significance of this particular spacing will subsequently be explained with reference to the practice of the present invention.

Accordingly, it will be appreciated by those skilled in the art that once the apparatus 10 is suspended in the well casing 12, the weight of the perforating apparatus will be sufficient to overcome the frictional restraint provided by the engagement of the bow springs 28 with the casing when it is desired to move the perforating apparatus downwardly into a selected position adjacent the earth formation 15. It will be recognized, of course, that upon downward travel of the perforating apparatus 10 through the casing 12, the weight of the carrier 18 will shift it downwardly in relation to the anchoring assembly 24 so as to place the opposed shoulders 29 and 31 into engagement with one another. Conversely, upward travel of the perforating apparatus 10 through the casing 12 will shift the carrier 18 upwardly in relation to the anchoring assembly 24 until the opposed shoulders 30 and 32 are brought together. Moreover, until one or the other of the two associated pairs of the opposed shoulders 29-32 are respectively engaged, the carrier 18 can be freely moved over a selected span of longitudinal travel relative to the anchoring assembly 24whenever the assembly is stationary in relation to the casing 12. Thus, as will subsequently be seen, when the perforating apparatus 10 is employed for practicing the methods of the present invention, it will be appreciated that it is particularly important that the anchoring assembly 24 can be selectively stationed at a desired location in the casing 12 for providing a temporarily-fixed support along which the carrier 18 can be moved in relation thereto between upper and lower positions having a predetermined longitudinal spacing. This predetermined spacing is, of course, established by the longitudinal spacing between the opposed shoulders 29 and3l (as well as the shoulders 30 and 32).

Those skilled in the art will, of course, appreciate that there are many control systems for selectively detonating a plurality of shaped charges by successive electrical signals. In general, these control systems function to selectively supply an electrical current of sufficient magnitude for detonating electrically-responsive detonating means such as a blasting cap connected to a detonating cord or an explosive initiator, as at 35 and 36, operatively associated with each of the shaped charges, as at 21 and 22. For example, FIGS. 1 and 5 of U.S. Pat. No. 3,246,707 respectively show two control systems by which a first set of one or more shaped charges can be selectively detonated by a first electrical signal; and then, only upon closing of a switch, a second set of one or more shaped charges is enabled for detonation by a second electrical signal. Similarly, U.S. Pat. No. 3,327,791 as well as U.S. Pat. No. 3,380,540 also illustrate electrical control systems respectively employing a selectively-actuated switch for independently detonating two or more sets of shaped charges in succession in response to successive electrical signals. Thus, those skilled in the art will appreciate that appropriate electrical circuits can be readily arranged in the apparatus 10 in such a manner that the controlled actuation of an electrical switch can be employed to selectively enable first and second sets of one or more shaped charges, as at 21 and 22, for successive detonation upon successive applications of electrical current to the suspension cable 1 1.

Accordingly, as schematically illustrated in FIG. 1, the electrical control system 17 for the perforating apparatus 10 includes an electrical switch 37 of suitable design which is mounted in a fluid-tight chamber 38 on the carrier 18 and cooperatively associated with a longitudinally-movable actuating rod 39 arranged for selectively shifting the switch between its switching.

positions in response to longitudinal movements of the carrier in relation to the anchoring assembly 24. As depicted in FIG. 1, the switch 37 is a single-pole doublethrow switch having its movable switch member connected by an electrical conductor 40 to the central conductor 41 of the suspension cable 11. One of the switch contracts is connected by means of an electrical conductor 42 to the electrically-responsive initiator 35 for the shaped charge 21; and the other switch contact is connected by an electrical conductor 43 to the electrically-responsive initiator 36 for the second shaped charge 22. The metallic armor sheath 44 of the suspension cable 11 is electrically connected to the body of the carrier 18 to serve as a return path for the flow of electrical current to the surface from the initiators 35 and 36.

It will be appreciated, therefore, that the electrical control system 17 cooperates for selectively connecting the power supply (not shown) at the surface to the initiators 35 and 36 for the shaped charges Hand 22 according to thelongitudinal position of the carrier 18 relative to the anchoring assembly 24. Thus, if the perforating apparatus is positioned in the casing 12 so as to elevate the carrier 18 in relation to the stationary anchoring assembly 24 as shown in FIG. 1, the switch 37 will be effective for enabling the shaped charge 21 for selective detonation and electrically isolating or disabling the other shaped charge 22. Conversely, as shown in FIG. 2, by cooperatively lowering the carrier 18 in relation to the stationary anchoring assembly 24, the switch 37 will be effective for connecting the initiator 36 of the other shaped charge 22 to the central cable conductor 41 and similarly isolating the initiator 35 of the shaped charge 21. Any reasonable number of shaped charges can, of course, be respectively associated with the two illustrated charges 21 and 22 so as to be simultaneously detonated as these two shaped charges are successively detonated.

Accordingly, to employ the perforating apparatus 10 I for practicing the methods of the present invention, the tool is lowered into the casing 12 by the suspension cable 11 for positioning the carrier adjacent to the formation 15. It will be recognized, of course, that inasmuch as the power supply (not shown) at the surface typically includes suitable disconnecting circuits (not shown), there is no danger of prematurely actuating either of the shaped charges 21 and 22 irrespective of the particular position of the switch 37. Thus, as the perforating apparatus 10 is initially being positioned in the casing 12, longitudinal shifting of the carrier 18 in relation to the anchoring assembly 24 will harmlessly actuate the switch 37 without creating a safety hazard since the source of electrical detonating current (not shown) at the surface will be disconnected from the cable conductors 41 and 44 until just before it is desired to practice the methods of the present invention.

Accordingly, once the perforating apparatus 10 has reached a position adjacent to the formation 15, the carrier 18 is shifted a short distance upwardly (by reeling in the suspension cable 11 from the surface) and then halted. As the cable 11 is moved upwardly, the carrier 18 will, of course, shift upwardly in relation to the stationary anchoring assembly 24 as depicted in FIG. 1. With this being the case, the switch 37 will be effective for first connecting the initiator 35 for the shaped charge 21 to the central cable conductor 41. Thus, upon application of sufficient detonating current from the power source (not shown) to the surface ends of the cable conductors 41 and 44, the shaped charge 21 will be detonated for producing a first perforation 45 through the casing 12 and the cement 14 and on into the earth formation 15.

As schematically represented in FIG. 2, once the first perforation 45 is produced, the carrier 18 is then slowly lowered by appropriately moving the suspension cable 11 for positioning the second shaped charge 22 very close to the previous position of the first shaped charge 21 when it was actuated for producing the first perforation 45. When the perforating apparatus 10 is being employed for practicing the methods of the present invention, it will be appreciated that the positioning of the second shaped charge 22 is accomplished by simply lowering the carrier 18 so as to bring the shoulders 29 and 31 into engagement with one another without producing a corresponding downward movement of the still-stationary anchoring assembly 24. Thus, as illustrated in FIG. 2, once the carrier 18 is shifted downwardly in relation to the frictionally-supported anchoring assembly 24, the switch 37 will be effective for connecting the initiator 36 for the second shaped charge 22 to the central cable conductor 41. Then, once sufficient detonating current is applied to the surface ends of the cable conductors 41 and 44, the shaped charge 22 will be detonated to produce a second perforation 46 closely paralleling the first perforation 45. To further assure the accuracy of the positioning of the second shaped charge 22 when it is detonated, the power source (not shown) can be left connected to the cable conductors 41 and 44 after the first charge 21 is detonated. This will serve to detonate the second shaped charge 22 immediately upon actuation of the switch 37 to connect the initiator 36 to the conductor41.

As previously mentioned, the carrier 18 can be arranged to carry any reasonable number of longitudinally-spaced shaped charges, with the only requirement being that the individual initiators (as at 35) for every other one of the charges (as at 21) are connected to the conductor 42 and that the initiators (as at 36) for the remaining or alternate shaped charges (as at 22) are connected to the conductor 43. As a result, when the first shaped charges, as at 21, are detonated, there will be a first group of widely-spaced perforations similar to the perforations 45 produced at intervals along the casing 12. Similarly, when the second shaped charges, as at 22, are detonated, a second group of perforations will be produced in the casing 12, with each of these being respectively located immediately adjacent to each of the first group of perforations so as to be substantially contiguous therewith. Each associated set of these first and second groups of perforations will, of course, be spaced relative to one another in the same manner as the illustrated perforations 45 and 46. It should be noted that although the longitudinal spacing between the associated perforations, as at 45 and 46, in a given set of paramount importance to the present invention, the spacing between adjacent sets of these perforations is discretionary. It should also be noted that other pairs of shaped charges need not be angularly oriented in the same lateral direction as are the shaped charges 21 and 22. For example, each pair of the shaped charges, as at 21 and 22, could just as well be faced in other lateral directions such as in angular increments of Referring now to FIG. 3, it will be appreciated that once the perforating apparatus 10 is moved into position adjacent to the formation 15 for practicing the methods of the present invention, detonation of the first shaped charge 21 will produce the perforation 45 along the perforating axis 33. The detonation of the shaped charge 21 will produce a perforating jet which, as is well known in the art, will leave debris such as a slug 47 in the forward portion of the perforation 45 as well as a relatively-impermeable sheath or layer of debris, as at 48, lining the walls of at least a substantial portion of the perforation. Moreover, by experiments with simulated test targets, it has been found that the second perforation 46 along the perforating axis 34 which substantially parallels the first perforation 45 and is in close proximity thereto. In this manner, as seen in FIGS. 4-6, the close proximity of the perforations 45 and 46 produced in accordance with the methods of the present invention will be such that debris, as at'50, and the envelope 51 of crushed compacted formation materials which would otherwise constitute the walls of the second perforation will instead be displaced into the overlapping perforations by the force of the second perforating jet so as to leave at least portions, as at 52, of their common side walls relatively free of these unwanted flow-blocking materials. Those skilled in .the art will, therefore, appreciate that the displacement of at least substantial portions of the envelopes 49 and 51 as well as the debris and other loose materials, as at 48 and 50, which will otherwise define a relatively-impermeable barrier around the perforations 45 and 46 will greatly enhance the subsequent flow of fluids, as at 53, from the formation into the well casing 12. Production of connate fluids will, in time, flush at least a substantial quantity of these loose materials from the perforations 45 and 46 to clear them for subsequent treating operations as well as improved production flows.

It will be recognized that by placing the second perforation 46 close to the first perforation 45, debris and the like will be displaced from the second perforation into the first. As an alternative mode of orienting the shaped charges 21 and 22, they could be arranged so that their respective perforating axes will be slightly convergent so as to result in a somewhat-longer common boundary or overlapping portions of the perforations 45 and 46. Otherwise, the net result of such slight convergence of the perforating axes will be the same as that obtained by the precisely-paralleled perforating axes 33 and 34.

Accordingly, it will be appreciated that the present invention has provided new and improved methods by which one or more sets of closely-grouped perforations can be produced at selected intervals along the well bore, with these perforations being at least partially cleared of crushed formation materials surrounding the walls of the perforations to subsequently impede the flow of fluids therethrough. By selectively actuating shaped charges for producing one or more sets of perforations at closely-spaced longitudinal intervals with the perforations either being parallel to one another or approaching a slight convergence in respect to each other, the first perforation will serve as a receptacle for at least a substantial part of the compacted, crushed formation materials which would otherwise tend to line or surround the walls of the perforation. Moreover, by sloughing of such flow-blocking materials from the adjacent or contiguous wall portions of the two closelyspaced perforations, the net result will be that substantially-permeable walls will be left on opposite sides of the spaced perforations.

While only a particular mode of practicing the invention has been shown and described, it is apparent that changes and modifications may be made without departing from this invention in its broader aspects; and, therefore, the aim in the appended claims is to cover. all such changes and modifications as fall within the true spirit and scope of this invention.

What is claimed is: j

1. A method for completing a well bore traversing earth'formations believed to be formed of competent materials and comprising the steps of: perforating a first surface of the well bore for producing a first perforation extending into the earth formations; and, thereafter, perforating a second surface of the well bore to produce a second perforation in the earth formations having a portion thereof contiguous with and substantially parallel a portion of said first perforation for displacing disrupted formation materials from between said contiguous portions into said first perforation.

2. The method of claim 1 wherein said first well bore surface is longitudinally spaced from said second well bore surface.

3. A method for completing a well bore traversing earth formations believed to be formed of competent materials and comprising the steps of: perforating a first surface of the well bore for producing a first perforation extending into the earth formation and surrounded by an envelope of compacted crushed formation materials; and, thereafter, perforating a second surface of the well bore to produce a second perforation substantially parallel to said first perforation extending at least partially into said envelope of compacted formation materials for displacing at least a portion of said compacted formation materials in said envelope away from said second perforation and into said first perforation to clear at least a part of said second perforation of flow-blocking materials. 7

4. The method of claim 3 wherein said first well bore surface is longitudinally spaced from said second well bore surface.

5. A method for completing a well bore traversing earth formations believed to be formed of competent materials and comprising the steps of: positioning a first shaped explosive charge at a first location in the well bore adjacent to the earth formations; detonating said first shaped charge for providing a first perforation extending along a perforating axis into the earth formations and which is surrounded by an envelope of disrupted formation materials; positioning a second shaped explosive charge at a second location in the well bore adjacent to said first location for aligning the perforating axis of said second shapedcharge with a region of said envelope of disrupted materials and substantially to said perforating axis of said first shaped charge; and detonating said second shaped charge to develop a perforating jet for producing a second perforation adjacent to said first perforation as well as for displacing at least a portion of said disrupted materials lying in said region between said perforations into said first perforation to clear said second perforation of flow-impeding matter.

6. The method of claim wherein said first and second locations are spaced one above the other.

7. The method of claim 5 further including the step of: producing connate fluids from the earth formations for flushing said flow-impeding matter into the well bore.

8. A method for completing a well bore traversing earth formations believed to be formed of competent materials and comprising the steps of: mounting an equal number of first and second shaped'explosive charge means at spaced intervals on a body adapted for positioning in the well bore; positioning said body in the well bore for directing said first shaped charge means at the earth formations; detonating said first shaped charge means for producing a corresponding number of first perforations extending into the earth formations and which are respectively surrounded by an envelope of crushed compacted formation materials; repositioning said body in the well bore for respectively directing each of said second shaped charge means at anadjacent one of said envelopes of crushed compacted formation materials; and detonating said second shaped charge means to develop a corresponding number of perforating jets respectively passing into said envelopes for producing a corresponding number of second perforations substantially parallel to said first perforations as well as for displacing at least a portion of said crushed materials from between said first and second perforations into said first perforations to clear at least said second perforations of flow-impeding matter.

9. The method of claim 8 wherein said first and second perforations are alternately distributed along the well bore.

10. The method of claim 8 wherein said first and second shaped charge means are alternately mounted along the length of said body and said body is repositioned in the well bore by moving said body longitudinally therein.

11. The method of claim 8 wherein said shaped charge means are all mounted in the same angular orientation on said body. 

1. A method for completing a well bore traversing earth formations believed to be formed of competent materials and comprising the steps of: perforating a first surface of the well bore for producing a first perforation extending into the earth formations; and, thereafter, perforating a second surface of the well bore to produce a second perforation in the earth formations having a portion thereof contiguous with and substantially parallel a portion of said first perforation for displacing disrupted formation materials from between said contiguous portions into said first perforation.
 2. The method of claim 1 wherein said first well bore surface is longitudinally spaced from said second well bore surface.
 3. A method for completing a well bore traversing earth formations believed to be formed of competent materials and comprising the steps of: perforating a first surface of the well bore for producing a first perforation extending into the earth formation and surrounded by an envelope of compacted crushed formation materials; and, thereafter, perforating a second surface of the well bore to produce a second perforation substantially parallel to said first perforation extending at least partially into said envelope of compacted formation materials for displacing at least a portion of said compacted formation materials in said envelope away from said second perforation and into said first perforation to clear at least a part of said second perforation of flow-blocking materials.
 4. The method of claim 3 wherein said first well bore surface is longitudinally spaced from said second well bore surface.
 5. A method for completing a well bore traversing earth forMations believed to be formed of competent materials and comprising the steps of: positioning a first shaped explosive charge at a first location in the well bore adjacent to the earth formations; detonating said first shaped charge for providing a first perforation extending along a perforating axis into the earth formations and which is surrounded by an envelope of disrupted formation materials; positioning a second shaped explosive charge at a second location in the well bore adjacent to said first location for aligning the perforating axis of said second shaped charge with a region of said envelope of disrupted materials and substantially to said perforating axis of said first shaped charge; and detonating said second shaped charge to develop a perforating jet for producing a second perforation adjacent to said first perforation as well as for displacing at least a portion of said disrupted materials lying in said region between said perforations into said first perforation to clear said second perforation of flow-impeding matter.
 6. The method of claim 5 wherein said first and second locations are spaced one above the other.
 7. The method of claim 5 further including the step of: producing connate fluids from the earth formations for flushing said flow-impeding matter into the well bore.
 8. A method for completing a well bore traversing earth formations believed to be formed of competent materials and comprising the steps of: mounting an equal number of first and second shaped explosive charge means at spaced intervals on a body adapted for positioning in the well bore; positioning said body in the well bore for directing said first shaped charge means at the earth formations; detonating said first shaped charge means for producing a corresponding number of first perforations extending into the earth formations and which are respectively surrounded by an envelope of crushed compacted formation materials; repositioning said body in the well bore for respectively directing each of said second shaped charge means at an adjacent one of said envelopes of crushed compacted formation materials; and detonating said second shaped charge means to develop a corresponding number of perforating jets respectively passing into said envelopes for producing a corresponding number of second perforations substantially parallel to said first perforations as well as for displacing at least a portion of said crushed materials from between said first and second perforations into said first perforations to clear at least said second perforations of flow-impeding matter.
 9. The method of claim 8 wherein said first and second perforations are alternately distributed along the well bore.
 10. The method of claim 8 wherein said first and second shaped charge means are alternately mounted along the length of said body and said body is repositioned in the well bore by moving said body longitudinally therein.
 11. The method of claim 8 wherein said shaped charge means are all mounted in the same angular orientation on said body. 